Improve the docs

docs/extras/countless.md

@@ -9,6 +9,10 @@ categories:
 
 Paginate without the need of any count, saving one query per rendering.
 
+!!!success
+If you don't need any frontend you should consider the [Pagy::Keyset pagination](/docs/api/keyset.md) that is even faster than countless, especially with big data
+!!!
+
 ## Setup
 
 ```ruby pagy.rb (initializer)

docs/extras/headers.md

@@ -76,18 +76,11 @@ If you are replacing any of the existing API-pagination gems in some already wor
 names so you will not have to change the client app that consumes them. You can do so by using the `:headers` variable _(
 see [variables](#variables) below)_
 
-### Countless Pagination
+!!!warning Countless and Keyset Pagination
 
-If your requirements allow to save one count-query per rendering by using the `pagy_countless` constructor, the headers will
-not have the `rel="last"` link, the `total-count` and the `total-pages` that are unknown with countless pagination.
-
-Example of HTTP headers produced from a `Pagy::Countless` object:
+If you use the `headers` extra with the [contless](countless.md) or [keyset](keyset.md) extras, a few heder will not be available (e.g. the last link)
+!!!
 
-```text
-Link <https://example.com:8080/foo?page=1>; rel="first", <https://example.com:8080/foo?page=2>; rel="prev", <https://example.com:8080/foo?page=4>; rel="next"
-current-page 3
-page-items 20
-```
 
 ## Variables
 

docs/extras/pagy.md

@@ -70,7 +70,7 @@ bar links (e.g. `countless` extra).
 
 ==- `pagy_next_url(pagy, absolute: false)`
 
-Return the previous page URL string or nil. Useful to build minimalistic UIs that don't use nav bar
+Return the next page URL string or nil. Useful to build minimalistic UIs that don't use nav bar
 links (e.g. `countless` extra).
 
 ==- `pagy_prev_a(pagy, **vars)`